1. Technical Field
The present invention relates to an antiseptic cap having a thread cover to enhance a seal between the cap and an access site to a body of a mammal. More particularly the invention relates to an antiseptic cap for attaching to an access site of an indwelling, central venous catheter and having a thread cover to enhance a seal between the cap and the access site.
2. Background Art
Catheters are widely used to treat patients requiring a variety of medical procedures. Catheters can either be acute, or temporary, for short-term use or chronic for long-term treatment. Catheters are commonly inserted into central veins (such as the vena cava) from peripheral vein sites to provide access to a patient's vascular system. Catheters offer many advantages for patients; for example, chronic catheters provide ready access without repeated punctures or repeated vessel cannulation for administration of large volumes of fluids, nutrients and medications and for withdrawal of blood on an intermittent basis. With respect to the use of catheters for infusion of fluids, examples include the infusion of drugs, electrolytes or fluids used in chemotherapy. In chemotherapy, catheters are used for infusion of drugs on an intermittent basis, ranging from daily to weekly. Another example includes the use of catheters in hyperalimentation treatment, wherein the catheters are usually used for infusion of large volumes of fluids.
For hemodialysis, catheters are commonly used—usually three times per week—for aspiration of blood for dialysis treatment and rapid return of the blood to circulation after treatment. Although a preferred mode of vascular access for a hemodialysis patient involves using an arteriovenous (AV) fistula of either the upper or lower extremities or an arteriovenous “bridge” graft (typically utilizing PTFE), use of these access devices is not always possible or desirable. When either of these modes of vascular access is not available, for example, due to a paucity of adequate blood vessels for creation of AV “shunts” or due to nonoptimally functioning established AV shunts, a large bore venous line catheter is typically required for hemodialysis. Catheters used for hemodialysis usually include two relatively large diameter lumens (usually molded as one catheter) for aspiration and rapid return of blood required during the hemodialysis procedure. One lumen of such a catheter is used for aspiration, or removal, of blood, while the other lumen is used for returning the blood to the patient's bloodstream.
Catheter connections, such as, for example, connections of catheters to dialysis machine tubing, to IV line tubing, to infusion ports and to catheter caps, which are used to seal the end of a catheter to protect the sterility of the catheter and prevent fluid loss and/or particle contamination, are most often made utilizing the medical industry's standardized Luer taper fittings. These fittings, which may either be male couplings or female couplings, include a tapered end of standardized dimensions. Coupling is made by the press-fit of mating parts. A threaded lock-fit or other type of securing mechanism is commonly utilized to ensure the integrity of the pressure fit of the Luer fittings.
Catheters, especially chronic venous catheters, provide challenges in their use. One such challenge is that such catheters can become occluded by a thrombus. In order to prevent clotting of catheters in blood vessels between uses, such as, for example, between dialysis treatments when the catheter is essentially nonfunctioning and dwells inside a “central” vein (i.e. superior vena cava, inferior vena cava, iliac, etc), the lumens of the catheter are often filled with a lock solution of a concentrated solution of the commonly used anticoagulant, heparin (up to 10,000 units of heparin per catheter lumen).
As used herein, the terms “lock solution” or “locking solution” refer to a solution that is injected or otherwise infused into a lumen of a catheter with the intention of allowing a substantial portion of the lock solution to remain in the lumen and not in the systemic blood circulation until it is desired or required to access that particular lumen again, typically for additional treatment, i.e., infusion or withdrawal of fluid. In addition, attention has been given to the development of alternative lock solutions with the goal of improving the patency rates of vascular catheters. For example, lower-alcohol containing locking solutions are under development wherein the lower alcohols include ethanol, propanol and butanol. Anti-microbial and or anticoagulant additives can optionally be added to the lower-alcohol containing locking solution. Preferably the lock solution can remain in the lumen for a desired amount of time lasting from about 1 hour to 3 or 4 days or longer.
For the reasons set forth above, significant care must be taken when infusing medications, nutrients and the like into a catheter, and when “locking” a catheter between uses, to minimize the risks associated with an indwelling catheter, including the risk of thrombosis or clotting, the risk of excessive anticoagulating and the risk of infection. Syringes are typically used to administer the required amount of catheter lock solution (determined by the catheter manufacturer) into an indwelling catheter after a given use. Flush procedures also require that care be taken to prevent blood reflux into the catheter. Reflux in I.V. therapy is the term commonly used to describe the fluid that is drawn back into the catheter after a flush procedure. The concern is that the reflux fluid contains blood or solution that could cause the catheter to occlude. To ensure that reflux does not occur, flush procedures suggest two techniques: 1) at the end of the flush solution delivery, the user maintains pressure on the syringe plunger while clamping the I.V. line; or 2) while delivering the last 0.5 ml of flush solution disconnect the syringe from the I.V. port or clamp the IV. line. Either technique maintains positive pressure on the fluid in the catheter to prevent reflux of fluid and blood.
In light of the above-described problems, there is a continuing need for advancements in catheter lock techniques, devices and procedures to improve the safety and efficacy of catheter locking procedures and of overall patient care.